There is currently a demand for heavy duty pneumatic tires to be improved in various performance areas. Such improvement may be realized through the design of tread patterns. Heavy duty tires are preferably improved in terms of heat build-up resistance for suppressing heat build-up while running and wear resistance for running on bad roads.
Technology for a heavy duty pneumatic tire is known that improves mud drainage in the contact patch without reducing the block rigidity and thus the wear resistance (see International Patent Application Publication No. WO 2014/002507). This heavy duty pneumatic tire includes, in a tread contact surface, two or more circumferential grooves extending continuously in the tread circumferential direction, lateral grooves opening to the circumferential grooves adjacent to each other in the tread width direction, and a block defined thereby. Each block includes one or more shallow grooves with an average groove depth less than the groove depth of the circumferential grooves adjacent to the block. The average groove depth of the shallow groove is greater than 20% of the groove depth of the circumferential grooves and less than 80% of the groove depth of the circumferential grooves. Additionally, at least one of the shallow grooves opens to at least one of the circumferential grooves adjacent to the block or the lateral groove.
In heavy duty pneumatic tires, mud drainage in the contact patch can be improved without reducing wear resistance. However, heat build-up resistance of heat build-up while running and wear resistance for running on bad roads has not been achieved.